CHARLOTTE — Mike Krzyzewski has written a book on defense. In it, there are a few absolutes: keep people out of your paint, no 3s, and no second shots. When it works, all five players in the man-to-man system play as one, moving in sync with each other and the ball.

That didn’t happen consistently last year.

“Nobody had a complete grasp of what we all were doing,” Krzyzewski said Wednesday during media day. “It was, ‘I think I’m supposed to be doing this, but what is he supposed to be doing.’”

The Blue Devils allowd 68.6 points per game, which ranked 10th in the ACC. Look at a few advanced stats, and the picture gets bleaker: Nationally, Duke ranked No. 251 in opponent turnover rate and No. 213 in steal rate.

This year, though, Krzyzewski said it will be easier to teach the team the basic Duke defense principles. The three seniors – Seth Curry, Mason Plumlee and Ryan Kelly – do have a grasp of the whole system. And they understand its importance.

“The biggest thing is that we have to be better defensively,” Plumlee said. “We weren’t a good defensive team at all last year. The games we were able to win, we just outscored people. When it mattered most, when we had to be able to stop someone, we couldn’t do that.

“When we needed to lock in and get a stop in the tournament, a guy like (Lehigh’s) C.J. McCollum, we couldn’t stop him.”

Part of the Blue Devils’ struggles stemmed from constant mismatches on the wing. Either Austin Rivers or Andre Dawkins, both 6-foot-4, were guarding bigger opponents. This year, Duke has a few more options with redshirt freshman Alex Murphy and newcomer Amile Jefferson, both 6-foot-8.

Since Krzyewski doesn’t think this is a particularly quick team, the Blue Devils will primarily pick up their men at halfcourt and won’t press unless necessary. The added length should help defend against the 3-point shot. And the experience and maturity of the three seniors, in a perfect world, will hold the system together.

It remains to be seen, though, how much Curry will be able to play. An unspecified leg injury has limited him in practice, and Krzyzewski said it’s the type of injury that could be bothersome all season. Marshall Plumlee, who Krzyzewski said is one of the team’s top six players, also is out at least a month with a stress fracture. At least initially, it will be Quinn Cook, Rasheed Sulaimon, Alex Murphy, Kelly and Plumlee who attempt to return Duke’s defense to the nation’s elite.

“Discipline is the biggest word,” Plumlee said. “You’re not playing one-on-one though. What makes the defense good is everybody working together and having each other’s back. A guy gets beat, so a wing player isn’t just looking at his man, he’s looking at the help side. When you have that, I think that’s what will help us become a better team.

“We’re confident in our team, we know we have a good team, and we know we’re talented, as we are every year. So, now it’s up to us, what are we going to do with the players and talent we have.”

Keeley 919-829-4556; Twitter @laurakeeley